1. Field of the Invention
The invention relates to the training, evaluation, and retraining of factors that limit human performance. Specifically, the invention relates to a method and apparatus for training, evaluating and reconditioning the performance of the hand, wrist, forearm, elbow and shoulder.
2. Description of the Related Art
Rehabilitation specialists are often asked to conduct an assessment of patients that have acquired a limitation to their optimal independent activity. Reconditioning or retraining of functional human performance is also an important goal of rehabilitation.
Although the parameters of human performance vary widely, one may identify several principles which are common to all forms of independent activity. Such common principles are muscular strength, endurance, joint range of motion, and motor coordination. It is these parameters of performance that the rehabilitation specialist will focus upon. The specialist directs attention upon the identified parameter's which are limiting performance and evaluates the degree of the limitation.
In the process of reconditioning, each of these principles will also be the focus of attention. Each of them will be enhanced by retraining therapy. The underlying physiological adaptations responsible for performance enhancement include, but not limited to, vascularity, cell biochemistry and motor coordination skills.
The methods used in both the assessment and retraining process of the muscle groups are closely related. Both procedures physically tax or overload the affected muscle group to quantify its performance and also to cause biological adaptations to improve the performance of that muscle group. Historically, the rehabilitation specialist will have a hands on approach using his own healthy limb to resist the movement of the patient's limb. In this way, the clinician evaluates the patient's performance through feel and, at the same time, offers exercise to the limited muscle group. By repetitive, hands on, accommodating exercise, the limited muscle group is overloaded and adapts biologically with improved performance.
For example, muscle strength is a performance parameter which is quite plastic in quickly adapting to immobilization or disuse as well as to increased activity or overuse. That is, muscle strength quite quickly increases or decreases with respect to use or disuse. Disuse, such as immobilization following injury or casting after surgery, results in a significant decrement in muscle size and hence muscle strength. In contrast, if free weight lifting is used as the method of choice for the rehabilitation therapy, the end result is a quick response of increased muscle cell size and hence gains in muscle strength.
Weight lifting equipment will overload a muscle group by using gravity against which a muscle must move the weight. With free weights, no controls are present to direct the speed of movement of the limb nor the resistance throughout the range of motion that the muscle must work against. The maximum free weight resistive load that can be applied to a limb is determined by the capacity of the associated muscle group as measured throughout the range of motion of the limb. The maximum load that the limb can support varies throughout its range of motion where at some point it is at a minimum and at another it is at a maximum. Hence, the maximum resistive free weight load that can be applied is equal to the maximum supportable load in the weakest area of the range of motion.
Conventional methods of subjective assessment and reconditioning, such as subjective "through the clinician's hands" evaluations and free weight exercise, are now reinforced with technology.
Technology has been developed which provides for assessment and reconditioning of muscular deficiencies by electronic control of the rate of movement of the limb. This rate of movement control is achieved by constantly varying the amount of resistance offered the moving limb throughout the range of motion. This category of devices are to allow the muscle group, usually a whole limb or limb segment, to accelerate to a pre-selected speed. These constant speed devices use the methods of isokinetic or accommodating resistance.
In the isokinetic system, once the moving limb achieves the selected speed, the device then offers the muscle group an accommodating resistance which is proportional to the contractile force such that the limb continues to move at the selected speed. These mechanisms usually have some form of position/time feed back, servo loop which directs the resistance, for example, through feeding a variable current to a DC servo motor, to be such that, no matter what constantly varying force is executed by the contracting muscle group, the limb does not exceed or fall below the speed selected.
The goal with isokinetic systems is that throughout the entire range of motion of the limb, the associated muscle groups are working at their utmost level while receiving an optimal overloading resistance.
The contractile effort of a muscle group against this type of microprocessor based resistance is registered by the system and produces a profile of contractile performance which is widely recognized as accurate and repeatable. The data from such a system can be used in a court of law as evidence in disability claims.
Examples of such isokinetic systems are the Cybex, manufactured by Lumex, U.S. Pat. No. 3,465,592, inventor J. Perrine; the LIDO manufactured by Loredan, U.S. Pat. No. 4,601,468; inventor M. Bond, KIN COM manufactured by Chattanooga, U.S. Pat. No. 4,711,450, inventor J. McArther; the Biodex, U.S. Pat. No. 4,628,910, inventor R. Krukowski and U.S. Pat. No. 4,691,694, inventor R. Boyd, et al.; and the devices disclosed in U.S. Pat. Nos. 3,848,467 and 4,235,437. Each of these systems use the method of isokinetic resistive exercise/assessment applied to the large muscle groups of the legs particularly the knee.
Attachments are also available to modify these devices to address the arms and, secondarily, the ankle, wrist and hand. With respect to the hand, gross movements are allowed by these systems which include a.) an attachment which simulates the grip motion one would use with pliers and b.) an attachment which has a moving rod element with the forearm rigidly fixed for simulation of certain wrist activities. In each case a specific work task is simulated with these accessories.
The shortcoming of these devices is that the movements described by the hand are those which are seen specifically at job sites or only rarely in life. Reliability of the assessment data is questionable with these systems due to the inability to accurately reproduce the same posture and set up for each trial. These devices are best suited to exercise muscle groups and areas of muscle groups. The assessment aspect of these devices is severely limited by the design.
Other devices have been developed with similar intentional designs limiting the use of the system to simulations of specific work tasks. For example, U.S. Pat. Nos. 4,337,050 and 4,768,783 issued to Engalitcheff, Jr. disclose a method and apparatus for rehabilitating injured muscles. Engalitcheff, Jr. teaches an apparatus which includes a number of specific accessory elements simulating various tools coupled to a controlled resistance device. These accessories allow the therapy to address the particular work tasks an individual may be expected to perform. Each accessory element is specifically adapted to the resistance device, which includes a rotatable shaft, controlled, in one embodiment, by an electric brake coupled to an adjustable voltage source. Ostensibly, selective resistance is provided to each of the variety of various accessories to permit exercise of specific muscles or joints in simulated industrial applications. Feedback regarding the amount of force applied to each particular exercise is provided by a voltmeter; no other type of data feedback is provided.
A more sophisticated rehabilitation system which also includes means for evaluating muscle degradation is the LIDO.RTM. WorkSET, manufactured by Loredan Biomedical, Inc., Davis, Calif. The Loredan device includes an adjustable resistance head, to which a number of accessories may be coupled, and various other tool-type accessories for simulating work-related activities. The resistance head generally includes a gear reducing element and a D.C. servo motor, appropriately sized to provide resistance for the various tool accessories. A personal computer controls the resistance applied to all accessories of the system, providing variable resistance to each of the accessories attached thereto for a series of exercise and evaluation modes. The Loredan system is capable of automatically implementing three general types of exercise for a test subject: isokinetic, isotonic and isometric exercise. The isokinetic exercise mode generally provides a variable force against the particular motion undertaken by subject with the exercise accessory to maintain a constant velocity on the test subject's action. The isotonic exercise mode provides a constant force against the test subject's actions to allow the subject to move the accessory device at varying speeds. The isometric exercise mode deals generally with the static measurement of the flexing and extension of particular muscles, including both concentric and eccentric contractions.
The Loredan system requires a physical floor space area of approximately 8' by 8', generally making it suitable only for large scale rehabilitative efforts. The numerous attachments are adaptable to allow rehabilitation of many muscle groups in a manner similar to the of the Engalitcheff, Jr. devices.
Disuse atrophy, caused by such things as cast immobilization, results in a loss in human performance by negatively effecting muscular strength, endurance, joint range of motion, and motor coordination skills. Disuse can be a consequence of a variety of factors, including being forced into a bedridden condition following traumatic injury. Another circumstance that can bring about disuse atrophy is living in a weightless environment. Clearly, the degradation of muscular systems of astronauts can have a deleterious effect not only on the success of any particular flight mission, but the basic safety of all members of the flight vehicle crew. As noted above, exercising particular muscle groups can prevent muscle deterioration. Studies have shown that individuals exposed to simulated weightlessness who exercised daily were able to maintain muscle strength in the particular muscles exercised. In particular, isokinetic exercise of particular muscle groups has been found clearly effective in maintaining muscle strength under conditions of simulated weightlessness. Naturally, it would be desirable to provide astronauts on flight missions with the means to effectively exercise muscles to maintain muscle strength, particularly in key muscle groups.
Physical space and astronaut time are at a premium on all space flight missions. The machines discussed above are generally not suitable for use on flight missions because of the physical space required for their effective operation. For example, the Loredan device, while providing a comprehensive means to evaluate and recondition loss of performance, is prohibitively large to allow its use on, for example, the Space Shuttle. Further, it is not an effective device to use for hand movements having the basis of its design a focus on large arm movements such as using a steering wheel of an automobile.
Further, exercise suitable for maintaining muscular strength must impose sufficient force and inertia on the muscles under treatment to maintain the muscular endurance of flight crews. One particular study has advocated the use of a treadmill; however, certification of such a device for the stresses to which it will be exposed in space flight use is a major endeavor.
It is also critical to determine the extent of any damage or loss of control to muscular groups on spaceflight missions. One apparatus for testing the strength and control of muscular systems of the hand is disclosed in U.S. Pat. No. 4,885,687 issued to Carey. Carey discloses a device which requires a test subject to trace a number of force patterns by altering the force of the subject's grip on a handgrip dynamometer and load cell. Carey provides a significant amount of quantitative data for evaluation of the subject's performance on each of a number of increasingly difficult tests. However, Carey provides no significant therapeutical means for improving the subject's performance. Further, Carey contemplates use of the subject's entire hand and is limited to testing contractile force of the basic hand grip. Thus, the data provided by Carey as to the condition of the muscles of the hand is rather limited.
Thus, an object of the invention is to provide a system for the comprehensive evaluation and correction of muscular systems of the human body.
A further object of the invention is to provide a comprehensive system for the evaluation and training of the human hand, wrist, elbow, and shoulder.
Yet another object of the invention is the provision of the above objects within compact physical dimensions making the system suitable for use on orbital vehicles.
Another object of the invention is to provide a evaluation and exercise system which is capable of testing and evaluating all cardinal movements of the human hand, including the individual fingers thereof.
Yet another object of the present invention is the provision of a novel means for controlling a testing and evaluation system.
Another object of the present invention is the provision of the above objects in a system which provides comprehensive, high resolution feedback to the control mechanism of the evaluation system, and also provides comprehensive feedback on the condition of the muscle groups under test by the evaluation system.
A further object of the present invention is the provision of the above objects in conjunction with an automatic software control system which automatically provides a series of testing and correction schemes.
A further object of the present invention is the provision of a control system including control software which simulates a variety of Activities of Daily Living (ADL) to measure the performance of the test subject and train the muscular groups associated with each activity.
A still further object of the present invention is to provide a system for evaluating and training the muscular systems of the human body which utilizes a unique ergonomic testing mechanism.
Yet another object of the invention is the provision of novel means for the application of isokinetic loading against the motions of the hand including the thumb and digits and upper extremity.
Yet another object of the invention is the application of isokinetic loading methods in motor coordination skill assessment specifically reaction time to mechanical movement and frequency of tapping/squeeze movements.
The present invention looks to applying the accepted methods of isokinetic assessment and reconditioning to the function of the hand by isolating cardinal movements of the hand.